1. Field of the Invention
The invention relates to a prefilter for a fuel delivery unit of a motor vehicle having a filter fabric, a connection piece for connecting to the fuel pump, and a support element for supporting the filter fabric.
2. Related Art
Prefilters are often used in present-day motor vehicles for the filtration of various fuels, such as diesel or gasoline. To produce a prefilter for the filtration of gasoline, a fabric blank corresponding to a layout of a finished prefilter is punched out from a synthetic fabric. This fabric blank is introduced into a plastic injection mold. In the injection mold, a plurality of support elements and a connection piece are injection-molded onto the fabric blank. So that the fabric blank can be fixed in the injection mold, tabs and protrusions are provided on the fabric blank. After the injection molding operation, the fabric blank is folded into the prefilter, and the margins are welded to one another and trimmed.
In filters intended for diesel fuel, a fabric blank is deep-drawn from a metal fabric for an upper part and a lower part. These fabric blanks are subsequently introduced individually into an injection mold, and the connection piece and support elements are injection-molded on. Finally, the two fabric blanks are laid with their margins one on the other and sealed by means of a frame.
The known prefilters have the disadvantage that they are very complicated to manufacture and require a large number of machining steps.